Most of us like to think that we are shielded against the elements inside the walls of our home or office buildings. This may be true for weather, but it's certainly not the case with fauna. Swarming around us at all hours of the day is what theoretical ecologist Jessica Green calls "the wildlife in the air." Inhabiting every cubic meter of air, she says, are up to 10 million cells of bacteria.

Green is one of the many ecologists and microbiologists (and architects) to delve into a fledgling sphere of scientific investigation that explores the ecosystems of the indoors. And, as you might expect, some researchers have already turned up what, at first glance, seem like unsettling results. Barcott references the work of Norman Pace, a University of Colorado biologist, as an example:

But it's important to remember that shower heads, toilet seats and pillows are just niches that help make up a much larger indoor ecosystem. What's more, it's becoming increasingly clear that not all the microbiota that inhabit these niches are necessarily harmful. Many of them, in fact, may be very beneficial to human health.

Parsing out the dangerous bugs from the beneficial ones, and figuring out how to manipulate a building's architectural features such that the latter organisms thrive, is one of the primary goals of Green, Pace and others. "Everything we've learned about outdoor environments happens indoors, too," Green tells Barcott. "Random birth and death events, competition for resources, and coevolution of different organisms." Learning to read these ecological events on a microscopic scale could revolutionize everything from the way we build our hospitals to how we organize our homes.